Throttle control for compound carburetors



D. M. GORDON THROTTLE CONTROL FOR COMPOUND CARBURETORS Filed March 6, 1952 June 15, 1954 2 Sheets-Sheet 1 INVENTOR. DWIGHT M. GORDON @X W77 ATTORNEY June 15, 1954 D. M. GORDON THROTTLE CONTROL FOR COMPOUND CARBURETORS 2 Sheets-Sheet 2 Filed March 6, 1952 INVENTOR. DWIGHT M. GORDON ATTORNEY Patented June 15, 1954 UNITED STATE TENT oFFI THROTTLE CONTROL FOR COMPOUND CAR-BURETORS Application March 6, 1952, Serial No. 275,060

7 Claims. 1

This invention relates to multi-stage carburetion systems for automative engines and consists particularly in novel means for rendering the secondary stage ineffective during the cold starting and warm-up periods.

In a co-pending application, Serial No. 263,291, filed December 26, 1951, in the names of Harold A. Carlson and James T. W. Moseley, there is illustrated a two-stage carburetor having serially opened primary and secondary throttle valves and an unbalanced thermostatic choke in the primary stage. There is also provided a locking device which is normally in its position for preventing opening of the secondary throttle or throttles. However, with this device, it has been found that if the primary throttle valve is opened widely during the warm-up period, causing the engine to race, the choke valve may be opened by air flow thereagainst sufficiently to release the secondary lock, permitting opening of the throttle. Since the engine may not be able to properly utilize the extra fuel mixture derived from the secondary stage, until it is fully heated, there may result a split or stumble in the engine operation with a consequent momentary loss of power just when acceleration is desired.

According to the present invention, this difhculty in avoided by providing the secondary stage locking device, as illustrated in the above mentioned co-pending application, with a pawl to latch the former in its locking position when the primary throttle valve is at least partly opened, the latch being released when the primary throttle is substantially closed.

In the accompanying drawings which illustrate the invention,

Fig. 1 is a side view of a two-stage, automotive carburetor embodying the invention.

Fig. 2 is a view of the opposite side of the carburetor.

Fig. 3 is a view of the throttle and choke interconnecting mechanism in Fig. l, but with these parts in different positions and with a part of the fast idle cam broken away.

Fig. 4 is a detail of the structure in Fig. 3 with certain parts removed to clarify the underlying structure.

Fig. 5 is a view of the choke and throttle interconnection parts in Figs. 1 and 2, but with these parts in still different positions.

Fig. 6 shows the primary and secondary throttle interconnection parts of Fig. 2, but with the primary throttle fully open and the secondary throttle locked closed.

The carburetor here illustrated is of the same secondary type as shown in the above-mentioned co-pending application and has four barrels formed in a central cluster with a common air horn structure I!) at the upper portion divided at the center by a partition ll. At the left-hand, forward side of the partition there is provided a shaft l2 jour" nalled in the walls of the air horn and mounting an unbalanced choke valve l3. Suitable thermosuction, automatic choke control mechanism, conveniently of the type illustrated in Coffey Patent No. 2,325,372, is mounted in housing is at one end of the choke shaft. In the lower parts of the mixture conduits are primary and secondar throttle valves I1 and 18 mounted on shafts it and 20. Fuel bowlstructure 2| extends entirely around the mixture conduits and closes the usual constant level controlling mechanisms (not shown) for controlling the supply of fuel through inlet 22.

A lever 23 is secured rigidly to one end of primary throttle shaft l9 (Figs. 1, 3, and 5) and has an aperture 24 for attachment by suitable linkage to the accelerator pedal in the drivers compartment. Lever 23 carries a fast idle adjusting screw 25 by means of inward, threaded lugs 26. Rigidly secured to the corresponding end of secondary throttle shaft 28, there is a disk 27 having a. radial lug 28 for a purpose to be described. Loosely mounted between the throttle Valves on a pivot stud 29 is a fast idle cam structure including a lever 38 and a separate cam element 3| yieldingly connected by a torsion spring 32 which normally maintains the lever and cam in their positions as shown, with a finger 33 on the lever abutting a recessed edge 34 of the cam. Also, loosely pivoted on stud 29 is an eccentrically weighted lever 35 having a finger 3t, normally held by the weight of the lever in the position shown in Fig. 1 so as to abut radial lug 28 on secondary throttle disk 2? and prevent opening of the secondary throttle. Lever 30 is connected by a link 31 to an arm 38 rigid with choke shaft l2 so that when the choke valve approaches its full open position, a peripheral, out-turned lug 39 on lever 30 engages an edge 40 on eccentric lever 35 so as to tend to urge the eccentric lever clockwise away from its secondary stage looking position.

Figs. 2 and 6 illustrate the throttle inter-connecting mechanism, including a small, collar-like lever rigid with primary throttle shaft i9 and having a pair of radial lugs 46 and 41. Loosely pivoted about the primary throttle shaft and just inside of tight lever 45 are a pair of loose levers l8 and 49. Lever 48 has a finger fall which is connected by a coiled, tension spring 5| to radial lug 4'? on tight lever 65. Lever 48 also has an outturned, peripheral lug 52, normally held in engagement with lug 45 on the tight lever by spring 5i, and an adjacent, inturned peripheral lug 53. Second loose lever 49 is connected by a link 5&- to an arm 55 rigid with secondary throttle shaft 28. Arm 55 is normally urged in the direction tending to close the secondary throttle by a coiled tension spring 56 anchored to a lug 5'1 on the carburetor body.

During normal opening of the throttle valves, after the choke valve is in its fully open, normal operating position so as to release the secondary throttle from the locking effect of eccentric lever 35, the secondary throttle remains closed until the primary throttle has reached a predetermined degree of opening, say 60, whereupon inturned lug 53 on loose lever 48 engages a shoulder 58 on second loose lever 49, as shown in so that continued opening of the primary throttle L tends to open the secondary throttle. Figure 6 represents a condition wherein the primary throttle ll has been substantially fully opened, while secondary throttle it remains locked in its closed position. This is possible because of the stretchof coiled spring 5! as shown. All of the above is more fully illustrated and claimed in the above mentioned co-pending application.

With the use of the above structure, should the primary throttle be fully opened, as in 5 and 6, during the warm-up period when eccentrio locking lever 35 prevents opening or" the secondary throttle, the rush of air past unbalanced choke valve 13 may be sufficient, as shown in Fig. 5, to move the choke valve and lug 39 on lever 35 connected to the choke against edge on the eccentric locking lever, and thereby unlock the secondary stage.

In order to prevent the locking lever from being shifted away from its locking position when the choke is in a warm-up position, according to the present invention, there is pivotally attached to the locking lever a latching pawl til having a semi-circular recess 62 in its lower edge normally seated, by the weight of the pawl, upon a latch pin i3 projecting from the carburetor body. Such latching of the pawl can prevail, of course, only when the eccentric locking lever 35 is in its secondary-stage locking position, as in Figs. 1 and 5. The pawl also has a downward projection 64, which engages one of the idle screw mounting lugs 26 on throttle lever 23 when the primary throttle is substantially closed, to lift the pawl from latch pin 63 and free eccentric locking lever 35 for clockwise shifting under the influence of the choke valve. Idle adjusting screw 25 engages fast idle cam 31 during cold starting and warmup, as is well known, to limit closing movement of the primary throttle valve. Obviously, whenever the primary throttle valve is substantially opened, and eccentric lever 35 in its secondary locking position, pawl 62 will engage latch pin S3 to prevent disengagement of the eccentric lever from lug 28 on secondary throttle disk El and, thus, prevent undesired unlocking of the secondary stage during the warm-up period.

While the carburetor has been described as having a single primary and a single secondary throttle, a plurality of such throttles may be provided and the carburetor may be provided with more than two stages. Also, the locking and latching features may be applied to a flow or suction actuated secondary-stage throttle con trol valve, which may be supplemental to the secondary throttle, wherein there is no mechanical connection between the primary or secondary throttle and the mentioned control valve to produce serial operation of the stages as the engine speed increases. The carburetor may be modified in these and other respects as will occur to those skilled in the art and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. In a multi-barrel carburetion system, a plurality of induction conduits controlled by throttle valves, means for successively opening said valves, a thermostatic device for afiecting the actuation of one of said valves by opening means, and an operative connection between said device and the other valve for aiiecting the operation of said device according to the position of said other valve.

2. In a multi-barrel carburetion system, a plurality of induction conduits controlled by serially opened throttle valves, a choke valve in one of said conduits, a device actuable by said choke valve for restricting opening of one of said throttie valves when said choke valve is at least partially closed, and an additional device for restricting opening of said mentioned throttle valve and shiitable from its valve restricting position responsive to closing of the other throttle valve.

3. In a multi-barrel carburetion system, a plurality of induction conduits controlled by throttle valves, means for serially opening said valves, a choke valve in one of said conduits, a device actuable by said choke valve for restricting opening of one of said throttle valves when said choke valve is at least partially closed, and additional device for restricting opening of said mentioned throttle valve and shiftable from its valve restricting position responsive to closing of the other throttle valve and substantial opening of said choke valve.

l. In a multi-barrel carburetion system, a plurality of induction conduits controlled by throttle valves, means for serially opening said valves, a choke valve in one of said conduits, a first device for locking one of said throttle valves closed, an operative connection between said device and said choke valve for shifting said device from its valve locking position when said choke valve is substantially opened, a second device for locking said mentioned throttle valve in closed position, and an operative connection between said second device and the other throttle valve for shifting said second device from its valve locking position when said other throttle valve is substantially fully closed.

5. In a multi-stage carburetion system, a plurality of fuel mixture conduits having serially openable throttle valves, an unbalanced valve in one of said conduits openable by direct action of air flow thereagainst, a thermostatic control for said latter valve, mechanism for locking one of said throttle valves, and means operatively connecting said mechanism, respectively, to said unbalanced valve and the other throttle valve for unlocking said first throttle valve when said unbalanced valve is substantially opened and said other throttle valve is substantially closed, coincidentally.

6. In a multi-stage carburetion system, primary and secondary fuel mixture conduits having throttle valves therein, means for serially opening said throttle valves, an unbalanced, thermostatic choke valve in one of said conduits, a locking device for said secondary throttle valve normally urged toward a position for locking said secondary throttle closed, a yielding, operative connection between said choke valve and said device for freeing said secondary throttle valve from said device when said choke valve is sub-- stantialiy opened, means for preventing shifting of said device from said locking position, and an operative connection between said means and said primary throttle valve for causing movement of said means into and away from its locking position, respectively, when said primary throttle valve is substantially opened and substantially closed.

7. In a multi-stage carburetor, primary and secondary mixture conduits having serially opened, primary and secondary throttles therein, a yielding, unbalanced choke valve in one of said conduits, primary and secondary throttle levers movable, respectively, with said primary and secondary throttles, a fast idle cam structure pivotally mounted adjacent said primary lever and cooperable therewith to limit primary throttle closing movement, an operative connection between said choke valve and said cam for shifting the latter responsive to movement of the former,

a locking device pivotally mounted adjacent said cam and said secondary throttle lever, means normally urging said device into a position for cooperating with said secondary throttle lever to lock said secondary throttle closed, an element on said cam structure for shifting said device from said locking position when said choke valve is substantially opened, a locking pawl carried by said device and normally urged, when said device is in said locking position, to lock said device in said position, irrespective of choke valve movement, and an element on said primary throttle lever for shifting said pawl from said locking position when said device is in its locking position and said primary throttle valve is substantially closed.

References Cited in the file of this patent UNITED STATES PATENTS Number 

